1. Beachwell Catchment
Seawater is extracted from the ground by 28 individual coastal beachwell units dispatched in 3 clusters. This specific type of catchment offers the following advantages:
- Highly flexible pumping design
- Very stable quality of seawater with constant salinity, low temperature amplitude and low pH
- Very low colloidal clogging or bio-fouling index (Silt Density Index SDI15<2)
- 28 beachwells (each 80m deep)
- Raw water capacity: 9,000 m³/h
Before passing through the Reverse Osmosis membranes, the extracted seawater must be treated with a two step filtration system. First, the water is treated by sand filters for large particle and bio-cell removal. Then, the seawater is ‘polished’ by micronic cartridge filters.
- 14 pressure media filters (sand filters)
- 11 micronic cartridge filters (5 microns)
3. High-pressure Pumps and Energy Recovery
To fight against the Osmotic Pressure and to comply with the required operating conditions, the seawater needs to reach a pressure level of 60 bar which is achieved by using high pressure pumps. This process is energy consuming. To optimize and reduce the final product price, Energy Recovery Devices (ERD) with a high recovery grade (97%) have been implemented.
- 8 high pressure pumps (60 bar)
- 24 ERD (97% efficiency)
- 40% energy reduction per produced m³ (in comparison with a conventional plant)
4. Reverse Osmosis (RO)
The separation of salt from seawater is achieved through high performance Reverse Osmosis (RO) membranes. The plant is equipped with more than 7,000 RO membranes which are the heart of the process and require great care to ensure high performance and a long life. Monitoring the operating data of RO membranes guarantees a final product that complies with the most stringent International Standards of potable water.
- First pass: 8 independent trains, each equipped with 114 pressure vessels (PV)
- Each PV contains 8 membranes
The demineralized water coming out of the Reverse Osmosis membranes is not potable yet. It has to be re-mineralized to comply with the potabilisation requirements.
Therefore, limestones are dissolved into the demineralized water with the help of CO2 injection which guarantees essential minerals (such as calcium and magnesium) in the final product.
- 4 limestone storage filters
- Limestone reactor size: 72m² each
6. Drinking Water Storage
Before storage, the potable water is disinfected and preserved with a Sodium Hypochlorite injection. The massive concrete reservoirs have been designed to store two days of potable water production in two separate tanks of 80,000m³ each.
- 2 reservoirs
- Total storage capacity: 160,000m³